This invention relates to a color film and method of its use where the film is one comprising a support layer, a light sensitive layer, and a water permeable color filter layer comprising a continuous phase transparent binder containing a random distribution of colored beads, said beads primarily composed of a water-immiscible synthetic polymer or copolymer.
The great majority of color photographs today are taken using chromogenic color film in which color-forming couplers, which may be incorporated in the film or present in the processing solution, form cyan, magenta and yellow dyes by reaction with oxidized developing agent which is formed where silver halide is developed in an imagewise pattern. Such films require a development process which is carefully controlled in respect of time and temperature, which is usually followed by a silver bleaching and a fixing step, and the whole process typically takes several minutes and needs complex equipment.
Color photography by exposing a black-and-white photographic emulsion through a color filter array which is an integral part of the film or plate on which the photographic emulsion is coated, has long been known to offer certain advantages of simplicity or convenience in color photography. Thus the Autochrome process, disclosed by the Lumiere brothers in 1906 (U.S. Pat. No. 822,532) exposed the emulsion through a randomly disposed layer of red, green and blue-colored potato starch grains, and the emulsion was reversal processed to give a positive image of the scene which appeared colored when viewed by light transmitted through the plate. The process allowed the formation of a colored photograph without the chemical complexity of later photographic methods.
The Dufaycolor process (initially the Dioptichrome plate, L. Dufay, 1909) used a regular array of red, green and blue dyed patches and lines printed on a gelatin layer in conjunction with a reversal-processed black-and-white emulsion system, which similarly gave a colored image of the scene when viewed by transmitted light.
Polavision (Edwin Land and the Polaroid Corporation, 1977) was a color movie system employing a rapid and convenient reversal processing method on a black-and-white emulsion system coated above an array of red, green and blue stripes, which gave a colored projected image. It was marketed as a still color transparency system called Polachrome in 1983.
These methods suffered a number of disadvantages. The images were best viewed by passing light through the processed film or plate, and the image quality was not sufficient to allow high quality prints to be prepared from them, due to the coarse nature of the Autochrome and Dufaycolor filter arrays, and the coarse nature of the positive silver image in the Polavision and Polacolor systems. The regular array patterns were complicated and expensive to manufacture. In addition, the films which used regular or repeating filter arrays were susceptible to color aliasing when used to photograph scenes with geometrically repeating features.
U.S. Pat. No. 4,971,869 discloses a film with a regular repeating filter array which claims to be less susceptible to aliasing problems. The film comprises a panchromatic photographic emulsion and a repetitive pattern of a unit of adjacent colored cells wherein at least one of the cells is of a subtractive primary color (e.g. yellow, magenta or cyan) or is of a pastel color. Scene information can be extracted from the developed film by opto-electronic scanning methods.
U.S. Pat. No. 6,117,627 discloses a light sensitive material comprising a transparent support having thereon a silver halide emulsion layer and a randomly arranged color filter layer comprising colored resin particles. The material has layer arrangement limitations and results in increased fogging of the sensitized layer. The patent discloses the preparation of a color filter array using heat and pressure to form the color filter layer prior to application of the light sensitive layer to a support. Due to the necessary use of pressure and heat, it is not practical to use the teachings of this patent to prepare a film having a light sensitive layer between the color filter layer and the support. Attempting to apply the needed heat and pressure to bond the filter layer to the rest of the multilayer would damage the light sensitive layer. The patent also discloses exposing, processing and electro-optically scanning the resultant image in such a film and reconstructing the image by digital image processing.
Color photographic films which comprise a color filter array and a single image recording layer or layer pack have the advantage of rapid and convenient photographic processing, as the single image recording layer or layer pack can be processed rapidly without the problem of mismatching different color records if small variations occur in the process. A small change in extent of development for example will affect all color records equally. Exceptionally rapid processing is possible using simple negative black-and-white development, and if suitable developing agents are included in the coating, the photographic response can be remarkably robust or tolerant towards inadvertent variations in processing time or temperature.
It is not a desirable film feature of the random color filter array type to have extensive overlap among the filter particles of different colors. This results in loss of light sensitivity and color inaccuracy.
It is also not a desirable film feature to employ a layer arrangement that requires one to expose the film through the support or bottom of the film since the light path is lengthened compared to the top side causing more scattering. Further, exposure through the support interferes with other uses of the support such as the application of magnetic layer and or an antihalation layer to the support.
A problem to be solved is to provide an alternative color film comprising a random color filter array.
The invention provides a color film comprising (1) a support layer, (2) a light sensitive layer, and (3) a water permeable color filter array (CFA) layer comprising a continuous phase transparent binder containing a random distribution of colored transparent beads, said beads comprising a water-immiscible synthetic polymer or copolymer.
Embodiments of the film provide color images that have improved quality compared to prior known films using a color filter array.